Subscribers visiting a foreign country are granted access to the mobile network in the visited country through roaming agreements. A roaming agreement is a mutual agreement between two mobile network operators; the home network operator (Home Mobile Network Operator, HMNO) and the visited network operator (Visited Mobile Network Operator, VMNO). A mobile operator must sign a large number of roaming agreements in order to offer global coverage for their subscribers. As an alternative to sign roaming agreements with operators in all countries around the globe, a mobile operator can buy roaming through Roaming Hub.
The roaming business is controlled by the telecom operators in the GSMA. Mobile Virtual Network Operators (MVNOs) and new network operators that relies on the infrastructure provided by MNOs, have no or limited possibilities to get their share of the profit from roaming.
Background art mainly focuses on the visitor situation from the subscribers' side. Numerous methods and technologies for roaming subscribers and multiple subscriptions exist. Commercially available products in this category are called Roaming SIM Cards, or Multi-IMSI SIM Cards.